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SFtraveler
- Junior | Next Rank: 30 Posts
- Posts: 21
- Joined: Mon Aug 30, 2010 11:51 am
Hey SFtraveler:
On the GMAT the easiest way to calculate using decimals is to not use decimals at all!
I'd multiply the numerator and denominator to get rid of the decimals in the denominator. To do that, you need to move that decimal place over three spaces to the right, so you have to multiply by 10 three times. That leaves:
20(.0003)/2 (I'll just stick to multiplying the common 2 term by 10 so that it stays simple)
Now the twos cancel, so you have:
10 * .0003
You can then move the decimal place once over to the right with that remaining 10, so you get:
.003
Generally speaking, when you see decimals, do whatever you can to turn them into fractions or integers. If you have place values preceded by a 0, you can multiply by 10 to get rid of the zeroes (either do the same to the top and bottom of a fraction to keep the value the same, or the same to both sides of an equation to keep the equation the same); if you have a term like .3333, convert that decimal to the fraction 1/3 so that you can work with the 1 and the 3 instead of a long, repeating decimal.
Decimals are great for use with calculators...but the brain (and the pen) works best with integers.
